A number of different machines and methods have been proposed to effect a compressive force on fibrous thread interlaced web material in order to impart pre-shrinkage properties. One such method and apparatus is disclosed in U.S. Pat. Nos. 2,765,513 and 2,765,514 both to Walton which disclose application of compressive forces along short columnar lengths of a fabric. The machine disclosed for imparting the compressive forces utilizes two spaced rolls rotating in opposite directions at different speeds and between which fabric is fed. A fabric indentor forces the fabric into the rubber surface of the faster rotating roll prior to the fabric being fed to the nip between the rolls with the result that a short columnar length of fabric between the indentor and nip is compressed. The method and apparatus has not been entirely successful in compressing all fabrics made up of fibrous thread interlaced web material since some fabrics, for example knit fabrics, have yarns which do not extend in lengthwise or columnar directions such that it is difficult to apply a compressive force to these yarns.
Other methods and machines have also used opposed rolls rotating in opposite directions at different speeds but utilizing a compactor shoe spaced from the faster moving roll rather than fabric indentors. In such instances, the faster moving roll acts as a feed roll to force a fabric material between it and the compactor shoe after which the material is fed to the nip between the rolls where the material is ironed to set the fibers or yarns in place. An example of this type of apparatus is disclosed in U.S. Pat. No. 3,015,145 to Cohn et al. A problem with apparatus of this type where opposed rolls rotating in opposite directions are utilized, as well as with the same type of apparatus as described above utilizing a fabric indentor, is that the faster rotating roll tends to scuff the material in the nip area making it difficult to treat material having dark colors.
Machines for effecting a compressive fibrous force on material have also utilized pairs of endless belts which are spaced from each other and which move in the same linear direction. The belts used are such that the linear speed of the surface of the belt may be changed by varying belt thickness with the result that when material fed between the belts is to be longitudinally compressed, the spacing between the belts is increased by decreasing the belt thickness which results in the surface speed of the belt being reduced so as to act as a retarding force on the material. Such a device is disclosed in U.S. Pat. Nos. 3,007,223 and 3,195,212 both to Wehrmann. The compressive effect utilizing belts however is limited by the belt thickness and construction. Further, the belts are relatively expensive and require extensive maintenance.
A still further apparatus and method has been disclosed which utilizes a straight movable member which is spaced from a stationary member where the movable member acts as a feed member to feed material through a space between the stationary member and a fixed retarding member in the form of a wedge to impart columnar type compression onto the material. Such a method is disclosed in U.S. Pat. No. 3,426,405 to Walton.
A difficulty with all of the methods and machines of which I am aware is that they do not provide means by which the fibers or yarns making up the material may be worked or kneaded while the material is in a compressed state in order that the fibers or yarns may slip relative to each other or, in the case of a knitted fabric, where the individual stitches may be repositioned due to the working or kneading action of the yarns.
Further, the prior art devices of which I am aware do not provide for means by which individual fibers or yarns comprising a web of material may move or slip with respect to each other due to any increase in diameter of the fibers or yarns resulting from puffing or swelling because of the application of heat and when the material is in a compressed or relaxed state.
It is therefore an object of my invention to provide for a method and apparatus for the compressive treatment of a fibrous material, for example a fibrous web material, whereby individual fibers making up the material may be kneaded or worked while compressive forces are being applied to the material.
It is a further object of my invention to provide for a method and apparatus for the compressive treatment of a fibrous material in which individual yarns or fibers of a material may be subjected to heat or steam in order that the fibers may puff or expand while the material is in a compressed state.